Materials used for artificial bones and artificial dental roots (hereinafter referred to as “bone-filling materials”) in dentistry, brain surgery, plastic surgery, orthopedic surgery, etc. are desired to have (a) no toxicity, (b) sufficient mechanical strength and (c) excellent compatibility with biological tissues.
Because porous calcium phosphate ceramics meets these conditions, they are utilized as bone-filling materials. When used as bone-filling materials, the porous calcium phosphate ceramics preferably have as high porosity as possible from the aspect of biocompatibility. However, because higher porosity leads to lower mechanical strength in the porous bodies, they cannot be used as bone-filling materials for portions needing high mechanical strength. Thus, porous calcium phosphate ceramics having both excellent biocompatibility and mechanical strength are desired.
JP 2000-302567 A discloses a sintered body comprising a body portion formed by substantially dense sintered calcium phosphate, and a surface portion formed by a finely ragged or porous sintered calcium phosphate layer. JP 2000-302567 A describes that fine raggedness or a porous sintered calcium phosphate layer on the surface of the porous sintered body increases a specific surface area, making it easy for osteoblasts to attach to the surface of the porous sintered body.
However, in order that a bone is formed in a bone-filling material embedded in a living body, bone-forming cells such as osteoblasts, etc. should be attached to the surface of the bone-filling material, and nutrition should be supplied to these cells. Even though osteoblasts were attached to the surface of the bone-filling material, a new bone would not be formed without nutrition. The sintered body of JP 2000-302567 A does not have a structure, to which proteins for forming blood vessels for sufficiently supplying nutrition to the osteoblasts are easily attached, failing to sufficiently accelerate the formation of a new bone.
The growth of blood vessels is caused by growth factors and/or inducers such as fibroblast growth factors (FGF), etc. The growth factors and/or inducers are proteins produced by cells. In order that the growth factors and/or inducers effectively function in the bone-filling material, etc., to improve the capability of the bone-filling material to form a new bone, the bone-filling material preferably has such a structure that the growth factors and/or inducers are trapped on its surface.